Apparently, nitric acid
content influenced the morphology, giving spheres as the prevailing output. No correlation was observed between the acid content and sphere size, but it apparently affected the rate of condensation and thus the spherical texture. When employing sulfuric acid (SA), multishapes were seen both at 1 SA and 2 SA (see Figure 5). Regardless of the content, a nonuniform mix of shapes was obtained including spheres (solid and hollow), small fibers, and whirling rods. At a higher molar ratio (3.34 SA), no product was obtained, suggesting that at high sulfuric acid ratios, the growth becomes extremely slow. Figure 4 SEM images of sample MS7 at different nitric acid contents. (a) 3.34, (b) 2.0, (c) 1.0, (d) 0.5, and (e) 0.2 mol relative to 100 mol water. Image (a) contains the corresponding TEM image. Figure 5 SEM images of sample MS12 at different sulfuric acid contents. (a) 1.0 and (b) 2.0 mol relative Apoptosis inhibitor to 100 mol water. No growth was observed with the 3.34 molar ratio. Microstructural properties studied by XRD and N2
Cytoskeletal Signaling inhibitor sorption isotherms were collectively presented for all samples in Figure 6 (sorption isotherms) and Figure 7 (XRD patterns) to clarify differences associated click here with each condition. These data were used to calculate the pore structural properties presented in Table 2. First, we will talk about the sample prepared at 3.34 NA which is the mutual counterpart of the silica fiber sample prepared using HCl; we will then discuss the effect of varying the acid content for both nitric and sulfuric acids. Figure 6 Nitrogen adsorption-desorption isotherms of
mesoporous silica prepared under Resminostat quiescent interfacial growth method. (a) All samples and (b) samples MS7 and MS12 prepared using various molar ratios of nitric acid (NA) and sulfuric acid (SA), respectively. Some isotherms were shifted upwards for proper comparison. Figure 7 XRD patterns of mesoporous silica products. (a) Samples MS7 and MS12 prepared at different molar ratios of nitric acid (NA) and sulfuric acid (SA) respectively and (b) all remaining samples. Sample MS12 at 3.34 SA is not shown because no product was grown throughout the growth period. As shown in Figure 6a, the sorption isotherms of the spherical silica precipitated at 3.34 NA M are very comparable to those of the fibers. The isotherms have type IV mesoporous isotherms showing capillary condensation step at p/po ~ 0.3 that is absent of any hysteresis. The relatively steep capillary condensation indicates a uniform size distribution with a pore diameter of 2.86 nm (compared to 2.35 nm of MSF) and respective surface area and pore size of 887 m2/g and 0.54 m3/g. The fibers and spherical particles possess comparable pore area properties except that the nitric acid causes a little swelling to the pore size. The pore order of the 3.34 NA sample is reflected in the XRD pattern in Figure 7a.